Electric lamp bulb holders



N ,1 A. H. WAGSTAFFE 77,

ELECTRIC LAMP BULB HOLDERS Filed Nov. 27, 1967 INVENTOR v A 'WAGST'AFF'E W lliam SMBQ' is ATTORNEYS United States Patent 3,477,062 ELECTRIC LAMP BULB HOLDERS Aubrey H. Wagstaffe, Lillington, Leamingston Spa, England, assignor to London Bankside Products Limited Filed Nov. 27, 1967, Ser. No. 685,757 Int. Cl. H01r 13/32, 13/54 US. Cl. 33988 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to contact-making holders for bayonet-capped electric lamp bulbs. It provides an improved and simplified construction of such holders, which can be applied to holders adapted to receive bayonetcapped bulbs of any existing size and type.

In all the many types of bayonet bulb holders now in use, the base or cap of the bulb is received within a securing frame and the bayonet members of the bulb are located against fixed portions of the frame by moving one or more supply contacts, movably mounted on the frame, into engagement with the contacts on the bulb. The moving contacts on the frame are ordinarily of spring construction, or are spring mounted. In the holders of the present invention, on the other hand, the locating frame itself is so constructed that by its engagement with the bayonet members of the cap it resiliently urges the bulb against the supply contact or contacts. This arrangement allows a very substantial simplification of the holder, with corresponding reduction in costs.

Particular, and at present preferred, embodiments of the invention are further described below with reference to the accompanying drawing, in which:

FIGURE 1 is a side view of one form of single-contact holder in accordance with the invention, shown with a supply lead connected thereto and a bulb inserted therein;

FIGURE 2 is a sectional plan view, taken on the line II--II of FIGURE 1 of one member of the holder of FIG- URE 1;

FIGURE 3 is a view corresponding to the lower part of FIGURE 1 of a double-contact holder;

FIGURE 4 is a view corresponding to FIGURE 2 of the construction shown in FIGURE 3;

FIGURE 5 shows a sheet metal blank for shaping into the spring frame used in the holder of FIGURES 1 and 2;

FIGURES 6 and 6a are plan and side views respectively of the blank of FIGURE 5 after a preliminary forming operation, and

FIGURES 7 and 7a are respectively plan and side views of the spring frame produced from the blank of FIG- URE 5.

The single-contact bulb holder shown in FIGURE 1 comprises a spring frame, a similar frame being shown separately in FIGURES 7 and 7a. It is suitably made from spring steel, in which case it can be produced by forming the flat blank shown in FIGURE 5, an intermediate stage of forming being shown in FIGURES 6 and 6a. However, other materials, such as suitable plastics, can be used for the spring frame, appropriate production methods being employed.

In its finished form, the spring frame 1 has a circular base 2, formed with a central hole and two part-cylindrical wall portions connected at diametrically opposite points to the base 2, each wall portion including a sub- "ice stantially rigid part 4, having an upper edge which is helically inclined, and a spring arm 5, which projects from the upper part of one portion 4 to near the top of the other portion 4 and then extends helically downwards, above and spaced from the inclined edge of that portion, the free end of the arm being close to the first portion 4.

The hole 3 in the base of the frame receives the reduced lower portion of an insulating washer 6, whose upper part bears against the upper surface of the base. A supply contact 7 is inserted in the washer 6 and connected to an electric supply lead 8, conveniently by soldering it thereto prior to assembly of the parts.

The cap of the lamp bulb 9 is received in the cylindrical cup constituted by the spring frame, the bayonet pins 10 of the bulb entering the helical slots formed between the parts 4 and 5 of the frame and causing partial rotation of the bulb as it is pressed axially into the holder. It will be observed that in the holder shown in FIGURE 1 this rotation is in an anti-clockwise direction, whereas the frame shown in FIGURES 7 and 7a is of opposite hand, requiring clockwise rotation of the bulb during insertion", both arrangements are equally effective. When the bulb is in position, as shown in FIGURE 1, the arms 5 bear resiliently against the pins 10 and urge the bulb towards the base 2 of the frame, thus pressing the contact 11 of the lamp bulb into engagement with the supply contact 7. The spring arms 5 terminate at their lower ends in locking portions 12 against which the bayonet pins 10 engage when the bulb is fully inserted. These locking portions may be upwardly inclined, or formed with indentations for the reception of the bayonet pins, to ensure absolutely secure locking of the lamp bulb. However, it has been found that it is sufiicient to form the portions 12 as horizontal extensions of the arms 5 (as shown in FIGURE 5), the flexure of the spring arms causing the portion 12 to assume an upward inclination (as shown in FIGURE 1) when the bulb is in position. Each bayonet pin is then located by the spring pressure of one arm 5, the adjacent vertical edge 13 of one part 4 and the engagement of the contacts. The gap left between the tip of portion 12 of the spring arm and the edge 13 is large enough to allow free movement of the spring arm, but too small to permit passage of the bayonet pin.

In the double contact holder shown in FIGURES 3 and 4, the spring frame 20 is generally similar to the frame 1 of FIGURES l and 2, but its base 22 is formed with two holes 23. These holes receive two tubular portions of an insulating member 26, the bores of the tubular portions receiving supply contacts 27 connected to supply leads 28. In order to accommodate small inequalities between the distances of the two contacts on the cap of the lamp bulb (not shown) from the line joining the two bayonet pins, the insulating member 26 does not bear flatly against the base of the spring frame 20, but is provided on its underside with a small rounded hump 26a, which permits limited rocking movement of the member 26 and the supply contacts 27 which it carries, thereby ensuring an equal pressure being applied between the two pairs of contacts. The controlled partial rotation of the bulb during insertion, caused by engagement of the bayonet pins 10 with the inclined upper edges of the parts 4 (FIGURE 1), safeguards against any risk that the supply contacts 27 will be short circuited by the lamp bulb contacts.

With the constructions illustrated, the supply contacts 7, 27, and the insulating members and supply leads associated with them are retained in the spring frame only by the pressure exerted upon them by the lamp bulb. If desired, means may be provided for retaining these contacts in position, even if no bulb is inserted in the holder. For example, one or more small rings of a material such as rubber may be engaged around the supply leads below the holder, the rings being large enough to prevent upward movement through the holes 3, 23 in the base of the frame.

It will be understood that the embodiments of the invention illustrated and described are intended as examples only and that many modifications of construction are possible. In particular, the supply contacts 7, 27 may be connected to the supply leads 8, 28 by many means other than soldering, including screw terminals, snap connectors, and many other known forms of connection. The frame of the holder is not necessarily symmetrical, as shown, but may be modified to acommodate lamp bulbs having bayonet pins which are off-set axially relative to one another, an arrangement which is adopted to ensure correct positioning in the holder of certain bulbs having two filaments which are separately energised. It will be understood also, that while for convenience of description it has been assumed that the lamp holder is located with its base downwards, the lamp bulb being inserted from above, the holder may in practice be used in any position whatever.

I claim:

1. A contact-making holder for a bayonet-capped electric lamp bulb comprising a frame for receiving and locating the cap of the lamp bulb and at least one supply contact carried by said frame, said frame comprising a portion of substantially cylindrical form within which the cap of the lamp bulb is received, the wall of this portion being cut away so as to provide slots for guiding and retaining bayonet pins on the cap and so that the part of the wall which borders each slot on the side remote from the supply contact or contacts constitutes a spring arm, adapted when the bulb is in position to engage resiliently against the corresponding pin to hold the cap against the supply contact.

2. A lampholder in accordance with claim 1 in which the wall of the cylindrical portion of the frame is so cut away that, when the holder is positioned with the supply contact at the lower end thereof the wall presents two substantially rigid portions, spaced apart circumferentially, each having an upper edge which is helically inclined, and two narrow and resiliently flexible strips, each of which is integrally connected to the upper part of one of the said portions, projects into close proximity with the upper end of the helically sloping edge of the other of said portions and extends helically downwardly above and spaced from that edge, defining therewith a slot for receiving and guiding a bayonet pin on the cap, the free end of the arm lying closely adjacent the first of said substantially rigid portions.

3. A lampholder in accordance with claim 1 in which the supply contact is located in an aperture in a base portion of the frame and is retained in positon by the pressure exerted thereon by the lamp bulb.

4. A lampholder in accordance with claim 1 in which two supply contacts are carried by a member which bears rockably against a base portion of the frame, so that it can tilt to ensure engagement between each of the supply contacts and a corresponding contact on the lamp bulb.

References Cited UNITED STATES PATENTS 2,848,702 8/1958 Jackson et al. 339 3,054,980 9/1962 Lennox. 3,344,388 9/1967 Parker et al 339-17 MARVIN A. CHAMPION, Primary Examiner JOSEPH H. MCGLYNN, Assistant Examiner U.S. Cl. X.R. 339-188 

